The present invention concerns novel polyether glycol derivatives of 2,5-dimercapto-1,3,4-thiadiazoles and their use as multifunctional additives for lubricating compositions.
Lubricating compositions ordinarily are formulated with various additives to enhance their performance. A problem sometimes encountered is that of compatibility between the various additives used. Therefore, it is desirable to use lubricating additives that can perform different functions.
Another occurring problem is that a particular additive or a combination of additives decreases the solubility of other additives in the lubricating composition resulting in undesirable haze or sediment formation. Dispersants or detergents are added to alleviate the problem.
Generally, lubricants contain additives known as antiwear agents which increase the load-carrying capacity of lubricants. The antiwear additives promote the formation of a surface film and thereby prevent wear of the contacting metal surfaces. During the course of use, lubricants are susceptible to deterioration due to oxidation. The oxidative process leads to the loss of lubricating properties and inadequate protection of the device to be lubricated. Antioxidants are added to inhibit the oxidative process. Therefore, it is desirable that antiwear agents possess antioxidant properties.
U.S. Pat. No. 4,140,643 describes a mixed reaction product which is rendered oil-soluble by reacting an oil-soluble dispersant with 2,5-dimercapto-1,3,4-thiadiazole and then reacting the intermediate with a carboxylic acid. British Pat. No. 1,462,287 describes multipurpose additives prepared by reacting the dimercaptothiadiazole with an oil-soluble dispersant.
It has been discovered that certain polyether glycol derivatives of 2,5-dimercapto-1,3,4-thiadiazoles display dispersant as well as antiwear and antioxidant properties.